Embodiments of the present invention relate to implanting ions in a substrate to form ion implantation regions.
Ion implanted regions are formed on a substrate to change the energy band gap level of material in a region of the substrate. For example, ions of boron, phosphorous arsenic, and other materials, are implanted in silicon or compound semiconductor materials to form semiconducting regions. As another example, ions are implanted in substrates comprising quartz, group III or group V compounds (e.g. GaAs), to form photovoltaic cells for solar panels. As yet another example, ions are implanted in substrates comprising gallium nitride to form light emitting diode (LED) for display panels.
However, in some ion implantation processes, a large percentage of the implanted ions evaporate or volatilize during the ion implantation process, or afterwards in subsequent processes. For example, diffusion and volatilization of implanted ions can occur in annealing processes which are performed after an ion implantation process is completed. As an example, ion implanted regions of a substrate comprising a silicon wafer are annealed to more uniformly distribute the ions in the implant regions, electrically activate the implant, and remove lattice defects. Such an annealing process can be conducted by heating the substrate to a temperature of at least about 950° C. However, the heat applied during the annealing process can cause the implanted ions to volatilize from the substrate, especially for high ion concentrations in shallow junctions.
For reasons including these and other deficiencies, and despite the development of various ion implantation methods and structures, further improvements in ion implantation technology are continuously being sought.